Vessel in dock (5)
I believe the answer is:
basin
This clue is a double definition.
'vessel' is the first definition.
(basin is a kind of vessel)
'dock' is the second definition.
(I've seen this before)
'in' acts as a link.
(Other definitions for basin that I've seen before include "Washbowl" , "Depression in the earth's surface" , "River-drained area" , "Land drained by a river" , "Stoup" .)